Ore-roasting furnace



. A2 She-ets-Sheet 1.v J. M. THOMPSON.

om: ROASTING FUENAGB.

N0.. 281,945. I 'Patented July 24, 1883.

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` `2 Sheets-Sheet 2\ J. THOMPSON.

y ORB ROASTINGPURNACB. No. 281,945. Patented July 24. 18.83..

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UNiTnn STATES PATENT Omron,

JAMES M. THOMPSON, OF SAN FRANCISCO, CALIFORNIA.

O RE-ROASTING FURNACE.

SPECIFICATION forming part offLetters Patent No. 281,945, dated July 24, 1883.

Application iledFebruary 16, 1880.

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Beit known that I, .Linus MONROE THOMP- SON, of the city and county of San Francisco, and State of California, have invented a new and useful Improvement in Ore-Roasting Furi naees, of which the following is a specification.

The invention relates to ore-roasting furnaces, and more especially to those, of whatever form or construction, in which the ore is exposed to the action ofthe draft and products of combustion from the fire-box, and still more especially those furnaces in which the ore is showered or lifted and dropped through the flames and products of combustion, and the liner portion of it in consequence carried back and out of the furnace by the draft.

The object of my invention is to provide a process and apparatus for roasting and means for cooling both the finer and coarser portions of the ore in one continuous operation, and in a more thorough and economical manner than has been or can be done by any of the means or processes heretofore employed to my knowledge.

rllhe invention consists in the construction and arrangement of a dust-precipitating chamber connecting with the iiue leading from the furnace (into which the dust77 or finer particles are carried by the draft from the furnace and precipitated) in such a inanner and position in respect to the furnace as to continuously return these finer particles back into the furnace, so that they are eventually roasted and deposited in the ore-chamber with the coarscr portion of the ore, and it also consists in the construction and arrangement of an ore-cooling pit77 in front' of and below the dischargedoor of the ore-chamber of an ore-roasting furnace, into which the ore is discharged and cooled preparatory to its further treatment, and without the employment of the wasteful, injurious, and disagreeable method of cooling it with water, and by which the waste heat is utilized for generating the heat for roasting the ore. Y

It also consists in providing a means of preventing some descriptions of ore, when being roasted in inclined cylinder-furn aces, from running down or passing too rapidly through the cylinder; and also in providing a means of adjusting the height of the bearings of a revolving cylinder-furnace (where three or more bearing-wheels are employed) to the unequal expansion of the different parts of the cylinder, which is produced by the difference in the degrees of heat at different points within it; and the invention further consists in the various novel combinations of the above-mentioned parts with each other and with other essential parts comprising the apparatus, all as will be more fully hereinafter set forth and claimed.

In the accompanying drawings, in which similar letters of reference indicate like parts, Figure l is a longitudinal view in part section. Fig. 2 is a front elevation, showing the orecooling pit and position of the fire-box and preeipitating-chamber. Fig. 3 is a section of the cylinder, showing arrangement and positions of interior transverse projections. Fig. 4 is an end view of the cylinder, showing both the longitudinal and transverse projections.

A is an inclined and continuously-acting open cylinder-furnace mounted upon and rotated by the bearing-wheels c a, and with its lower end projecting into the ore-chamber B, and into which the flames and products of combustion from the lire-box C enter and pass through and up the liuc D into the dust-precipitating chamber E, and through it up and out of the smoke-stack F into the open air.

G is the feed-hopper, from which and through the feed-pipe I) the ore, afterbeing pulverized, is continuously fed into the furnace.

The dust-precipitating chamber Eis divided by the partitions c c into any desired or practical number of passages or divisions connecting with each other and forming one continuous passage, d, which gradually enlarges from the inlet at the upper end of the flue D to the outlet at the base of the smoke-stack or chimney F. By gradually enlarging the passage d the arca of the air current or draft is gradually enlarged and its velocity correspondingly retarded, so that the finer ore particles which are carried into it from the furnace are allowed to fall and settle down to the bottom of the precipitatingchamber E. The entire area of the enlarged end of the passage d at the base, or connecting with the smoke-stack F, is covered with a scre'en or perforated partition, w, to prevent a reconcentration of the air current or draft before it passes entirely out of the IOO precipitating-chamber. The lower part of the precipitating-chamber E is made V or hopper shaped, in order to concentrate the ore particles more conveniently and return or feed them into the furnace. y

The broken lines x a: in Fig. l, Sheet l, indicate the shape of the precipitating-chambers when made hopper-shaped, and by which the use of an ore-conveyer could be dispensed with; but I prefer the construction shown in the drawings.

In order to prevent the ore from accumulating on the inclined sides of the precipitator or dust-chamber, 7 and to facilitate its collection at the bottom, I provide pivoted hammers m m, which are actuated by the camswa n on the shaft o, (which is rotated by the shaft of the feed or ore-conveyer f, or in any other convenient mannen) and which strike a constant succession of blows against the outside of the inclined sides of the dust-chamber E. The oreconveyerj in the bottom of the dust or precipitating chamber F, by having its flanges running in opposite directions from its center,

as shown in the drawings, affords simple and effective means by which the finer portion, which is precipitated in the enlarged end of the passage d, next the outlet to the smokestack F, is conveyed to and fed into the lower end of the furnace, and the coarser portion is conveyed in the opposite direction and fed or returned into the upper end of the furnace, with the ore from the hopper G, through the feed-pipe b, as shown, or separately into the upper end of the furnace, as desired.

The precipitating-chamber E is preferably constructed of sheet-iron, (of proper thickness, and of any dimensions and length that may be required, as the ore, after being precipitated to the bottom, can be easily conveyed any reasonable distance in both directions by the spiral flanges of the conveycrf, already described.

In order to scatter or shower that portion of the precipitated ore which is fed into the lower end of the furnace, a small air blast or current can be forced through the pipe g. (Shown in Fig. 1, Sheet 1.)

'Ihe ore-cooling pit His situated at any convenient position for discharging the ore from the ore-chamber B into it, and it is constructed with fines h under its bottom, which lead into an upright iiue or pipe, u, which is made of sufficient height and capacity to carry off the air which is heated in the iiues h by the ore, and cause a continuous current of air to pass into and through them. A pipe or passage,

j, also leads from the flues 7L into the ash-pit 7 or space under the fire-box C, to supply the air necessary to support the combustion within it, and the amount can be regulated by the valve k.

. The bottom of the ore-cooling pit is preferably made of iron, or other good heat-conduct ing material, to facilitate the cooling of the ore.

The central portion of the cylinder being subject to the greatest expansion, (owing to the combustion of the sulphur in the ore within it being at its greatest height in that part of the cylinder,) I support one end of one or more of the bearing -plates o on a spring, or the end of a weighted lever, p, so that when the cylinder expands that end of the bearingplate will be free to be depressed, but at the same time support its share of the weight of the cylinder.

The sustaining power of the weighted lever p can be regulated by moving the weight q a proper distance to or from the end of the lever p. By this means the breaking of the bearingwhe'els a, or their supporting or bearing plates 1", caused by the too great pressure on them, is avoided.

In Figs. 2 and 8, Sheet 2, is shown my device for preventing some descriptions of orcs,

during the process of roasting, from running downward and passing too rapidly through an inclined cylinder. For this purpose I form transverse projections s or iianges on the inner surface of the cylinder, which extend across and at right angles (or nearly so) between the longitudinal projections t. These transverse projections can be formed in straight lines cntirely around theinterior periphery of the cylinder A, as shown at the lower part of Fig. 2, Sheet 2; or each one can be formed independently of the other, as shown in the upper part of the same ligure, as may be preferred; and their position being at right angles to the lon gitudinal projections, they are therefore entirely unlike the diagonal ribs or projections for progressing the ore shown in my application for patent filed November 21, 1876, and are for exactly the opposite purpose, as before explained. rlhe action of these transverse flanges is entirely independent of that of the longitudinal projections t, and bear no relation whatever to that of the projections t; and, further, the result which would be accomplished by these transverse iianges in an inclined cylinder would be the same whether there were any of the longitudinal projections in it or not; and, finally, vthese transverse iianges would have no effect or action at all on the ore in a horizontal cylinder, and therefore are only intended and only claimed in an inclined ore-roasting cylinder.

I am aware that'in the Patent No. 181,7 7 G, September 5, 1876, to YV. O. Davis, a device for showering and progressing the ore upward through a rotating cylinder is shown which has some resemblance to my device above described; but the latter is unlike the former in many respects, and is for an exactly opposite purpose, as above explained, and could not serve the purpose or effect the result for which the former is intended and adapted; and I desire to restrict my claim to the particular construction and for the purpose only hereinabove described and set forth.

It is not absolutely necessary to locate the dust-precipitating chamber E above or higher than the furnace; but by so doing the necessity better draft is more easily obtained. Nor does IOO my present invention embrace such location or combination ofthe dust-precipitating chamber with a roasting-furnace as that shown and described in the patent of Napier and Thompson for ore-roasting furnace, No. 234,798, November 23, 1880; but my invention consists in precipitating the finer particles of the ore which are carried back by the draft, and in a continuous operation or manner returning or feeding their coarser portion into the upper end, and their finer portion into the lower end, of the furnace, as herein shown and described. Neither does my invention embrace the process of returning, in any manner or by any means, all the finer particles (which are carried back by the draft) into the upper end of the furnace, as that has heretofore been donein a crude manner by cleaning out the dust from the dust-chambers at intervals and mixing it with the ore, to be again fed with the ore into the upper end of the furnace; but my invention embraces the process of precipitating these finer particles and returning and feeding their coarser and finer portions into the upper and lower ends, respectively, of the roasting-furnace in a continuous and automatic manner as fast as they are carried back and precipitated; and also the means herein shown and described for continuously returning the coarser portion of these finer particles into the upper end, and at the saine time passing` or feeding their finer portion into the -lower end of the furnace as fast as they are precipitated.

The operation of my furnace is as follows: The ore is continuously fed through the feedpipe b into the upper end of the inclined revolving cylinder A, in which, by its rotation and inclination, the ore is showered or stirred and exposed to the heat and air and draft and products of combustion from the fire-box C, and the coarser portion, which will withstand the draft, is regularly progressed through the cylinder and roasted and deposited in the orechamber B, while the residue or finer portion is carried back by the draft and through the fine D into the dust-precipitating chamber E and precipitated to its bottom and continuously returned or fed by the screw-conveyer f into the furnace, the coarser portion being returned into the upper end of the cylinder and the ner portion f'ed into the top of the orechamber B, or lower end of the furnace, where it meets the coarser portion of the ore and is' carried with it down into the bottom of the ore-chamber B, and, being exceedingly fine, they are almost instantaneously roasted on coming in contact with the fiames and heated air and gases from the fire-box C, and also reduced to the proper condition for being carried down with the coarser ore into the orechamber B.

Should any of the fine ore particles which are fed into either end of the furnace be again carried by the draft through the fine D, they will be again precipitated in the dust-chamber E, and again returned into the furnace by the conveyer f, and this will be repeated until they are finally roasted and deposited in the orechamber B. y

In the roasting of most descriptions of ores containing considerable metal the entire portion which is carried back by the draft can be returned into the upper end of thcfurnace and finally carried through and roasted, while in the case of other ores containing less metals, it will be found best to feed the ner and lighter particles (which are precipitated in the end or part of the dust-ch amber next the smoke-stack) into the lower end of the furnace, while still other descriptions of ore containing chlorides, decomposed sul phurets, oxides, 81e. ,will bebetter treated by feeding all the portion which is carried back by the draft into the lower end 0f the furnace.

I am aware that furnaces and ore-chambers in which the surface of the ore is exposed to the heat of the furnace have been constructed with flues under their' bottoms for the purpose of drying and preparing the furnace for work, and for other various purposes. I therefore lay no claim to such, as my invention is for that of an ore-cooling pit, or, more properly, a hearth, having a low wall or inclosure around its sides, so as to retain and spread it as much as possible, and which is situated entirely outside of the furnace, and in or on which the orc is exposed to the cooling effect of the air, both above and below, as cannot be effected in the case of a furnace or ore-chamber constructed with fiues under its bottom.

I am also aware that in roasting-furnaces the' cylinders thereof have been provided on their interior with various forms of teeth, projections, &c., for breaking and mixing up the niaterial therein treated; but I layno claim to such devices, as I combine transverse flanges with longitudinal projections, as hereinbefore described, for the purpose of preventing the ore from fiowing too rapidly through the cylinder as it is rotated.

Having thus described my invention, what I claim is l. The process of roasting the finer particles of ore carried out of a roasting-furnace by the draft, which consists, first, in precipitating said ore particles; second, in separating the finer fromthe coarser precipitatedore particles; and, third, in simultaneously and continuously returning or feeding the separated coarser particles intovthe end of the furnace from which the precipitated ore was carried by the draft, and the separated finer particles or residue of the precipitated ore into the fire-box or end of the furnace into which the draft and products of combustion enter, while treating that portion of the ore which withstands the draft in the usual manner, substantially as herein described and set forth.

2. In an ore-roasting furnace, the dust-precipitatin g chamber E, arranged abovethe roasting-cylinder, and the reverse spiral conveyer f, arranged in the bottom of said precipitatingchamber, in combination with the ore-roasting cylinder A, ore-chamber B, and necessary de- IOO vices for connecting the same, substantially as described, and for the purpose set forth.

3. In an ore-roasting furnace, and for the purpose of exposing the surface of the ore to the action of the atmosphere,the ore-cooling pit H, located outside of such furnace,in combination with fines 7L 71located under the bottom of said pit and connecting With pipe u, substantially as described, shown, and for the purpose set forth.

et. In combination With the revolving cylinder A of a roasting-furnace, the bearing-plate r and Weighted lever @substantially as and for the purpose described. Y

5. The dust-precipitating chamber E,having `the graduallyenlarged passage or division d,

and screen or perforated partition w across or over its end next the smoke-stack, substantially as and for the purpose described.

JAMES MONROE THOMPSON.

fitnesses M. B. DODGE, INNEs I. NAPIER. 

